PNNL-20704 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Secondary Waste Form Down- Selection Data Package—Fluidized Bed Steam Reforming Waste Form NP Qafoku MM Valenta JH Westsik, Jr. RP Pires DM Strachan Septemeber 2011 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper. (9/2003) PNNL-20704 Secondary Waste Form Down- Selection Data Package—Fluidized Bed Steam Reforming Waste Form NP Qafoku MM Valenta JH Westsik, Jr. RP Pires DM Strachan September 2011 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 Summary The Hanford Site in southeast Washington State has 56 million gallons of radioactive and chemically hazardous wastes stored in 177 underground tanks (DOE/ORP 2010). The U.S. Department of Energy (DOE) Office of River Protection (ORP), through its contractors, is constructing the Hanford Tank Waste Treatment and Immobilization Plant (WTP) to convert the radioactive and hazardous wastes into stable glass waste forms for disposal. Within the WTP, the pretreatment facility will receive the retrieved waste from the tank farms and separate it into two treated process streams. These waste streams will be vitrified, and the resulting waste canisters will be sent to offsite (high-level waste [HLW]) and onsite (immobilized low-activity waste [ILAW]) repositories. As part of the pretreatment and ILAW processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility (ETF) on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed of in the Integrated Disposal Facility (IDF). To support the selection of a waste form for the liquid secondary wastes from WTP, Washington River Protection Solutions (WRPS) has initiated secondary-waste-form testing work at Pacific Northwest National Laboratory (PNNL). In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the ETF, PNNL is developing data packages to support that down-selection. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilizing and solidifying the liquid secondary wastes. This data package developed for the Fluidized Bed Steam Reforming (FBSR) waste form includes information available in the open literature and from reviewed and released data obtained from testing currently underway. The FBSR waste form is composed of two main components. The wastes are processed in the FBSR to form a granular product. This is the primary waste form. The granular product is then encapsulated in a binder material to form a monolithic form to limit dispersability and to provide some structural integrity for subsidence prevention in the disposal facility. At the Hanford Site, the FBSR process is being evaluated as a supplemental technology for treating and immobilizing Hanford low-activity waste (LAW) radioactive tank waste and for treating secondary wastes from the WTP pretreatment and LAW vitrification processes. The insoluble sodium aluminosilicate mineral form is the preferred FBSR product for the Hanford tank wastes because the solidified wastes will be disposed of in the IDF. The primary product from the FBSR process is a granular product composed of sodium aluminosilicate minerals. The sodium aluminosilicate FBSR granular product is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals (sodalite, nosean, and nepheline) with cage and ring structures that sequester anions and cations (Jantzen et al. 2007b). Nepheline is the basic sodium aluminosilicate mineral with the formula Na2O-Al2O3-2SiO2. When sulfates are captured within the cage structure, nosean forms with the formula 3Na2O-3Al2O3-6SiO2∙Na2SO4. When chlorides are captured within the cage structure, sodalite forms with the formula 3Na2O-3Al2O3-6SiO2∙2NaCl. Depending on the waste compositions, process additives such as magnetite are added to iron-bearing spinel minerals that sequester Cr and Ni in the waste. The FBSR process has been demonstrated at a pilot scale with nonradioactive simulants of Hanford Envelope C (AN-107) and Envelope A (saltcake) tank wastes and with a simulant of the LAW melter off- gas submerged-bed-scrubber liquid effluent. The process has also been demonstrated with the Idaho iii National Laboratory (INL) sodium bearing waste (SBW). The testing has been conducted with rhenium as a surrogate for technetium. Limited data are available on the behavior of 99Tc, although radioactive testing with a bench-scale steam reformer is currently underway. Previously, the FBSR waste form was evaluated as a supplemental treatment technology for the Hanford LAW. Extensive characterization work has been conducted on the FBSR granular product, including mineralogy, the Product Consistency Test (PCT), the Pressurized Unsaturated Flow (PUF) test, and the Single-Pass Flow-Through Test (SPFT). Work has been initiated to characterize the retention and release of radionuclides and constituents of concern, but much more work is needed. Only limited work has been conducted to characterize the FBSR waste form as a waste form for Hanford WTP secondary wastes. A number of different binders including cements and high-aluminum cements, geopolymers, hydroceramic cements, and Ceramicrete have been evaluated at the laboratory scale for encapsulating the FBSR granular product to form a monolithic waste form. A geopolymer was selected for the most recent FBSR waste form characterization but a final decision on the binder material has not been made. The FBSR granular product encapsulated in a binder to form a monolith waste form will meet waste acceptance criteria for IDF. The FBSR process produces a dry granular material. Any free liquids would be introduced through the encapsulation process, and that process can be controlled to minimize/eliminate free liquids. The FBSR waste form has been shown to pass the Toxicity Characteristic Leaching Procedure (TCLP) required to meet IDF dangerous waste limitations. As with any waste form, if the concentrations of the constituents of concern are too high, the waste form will not pass TCLP. At the expected concentrations in the secondary wastes, the FBSR product will easily pass TCLP. The FBSR waste form monoliths pass the 500-psi compressive strength requirement. Candidate binders include cements, geopolymers, and Ceramicrete. Using rhenium as a surrogate for technetium, the FBSR waste form in the GEO-7 geopolymer binder has been shown to meet the target diffusivity for technetium for secondary wastes. iv Acronyms and Abbreviations ANS American Nuclear Society ANSI American National Standards Institute ART Advanced Remediation Technologies ASTM American Society for Testing and Materials (ASTM International) BET Brunauer, Emmett, and Teller BSR bench-scale steam reformer BSSR bench-scale steam reformer CFR U.S. Code of Federal Regulations COC constituent of concern CRR carbon reduction reformer DE-Ci dose-equivalent Curie DI deionized (water) DMR denitration and mineralization reformer DOE U.S. Department of Energy DST double-shell tank Ecology Washington State Department of Ecology EM Environmental Management EMF electromotive force EPA U.S. Environmental Protection Agency ES emission spectroscopy ESTD Engineering Scale Technology Demonstration ETF Effluent Treatment Facility FBSR Fluidized Bed Steam Reformer GAC granular activated carbon HEPA high-efficiency particulate air (filter) HLW high-level waste HTF high-temperature filter ID inner diameter IDF Integrated Disposal Facility ILAW immobilized low-activity waste INEEL Idaho National Engineering and Environmental Laboratory INL Idaho National Laboratory LAW low-activity waste LDR Land Disposal Restrictions LERF Liquid Effluent Retention Facility LI leachability index v LLW low-level